It is known in the field of artificial eye lenses, consisting of intraocular lenses and contact lenses, that one method of manufacturing such lenses is by molding where the lens being manufactured is totally enclosed by a mold in contrast to lathe cutting or spin casting. Typically, the mold consists of two pieces mated together after a monomer mixture is placed in the concave portion of one of the mold pieces.
This process of molding is known in the art and is described for contact lenses, for example, in U.S. Pat. Nos. 4,565,348 and 4,640,489. One of the obstacles to be overcome in such a process is the appropriate placement and fixation of the mold pieces after the monomer has been placed into the concave portion of one mold and prior to polymerization.
Another requirement of any method used to fix the mold pieces together is that after polymerization of the monomer into a lens, the pieces must be easily separated in order that the contact lens can be removed.
A variety of traditional methods are satisfactory and appropriate in a non-production laboratory situation for placing one mold piecing upon another and then securing the two pieces in a relatively fixed position such as by weighting or clamping.
When considered with the requirement that the mold pieces be easily separable after polymerization of the monomer into a contact lens and that the fixing and separating process needs to be part of an automated high speed manufacturing process, it can be appreciated that methods and apparatus appropriate for accomplishing the above requirements on a small scale may not translate into acceptable methods and apparatus in production. Not only is speed of great importance, but the mold pieces must be fixed in such a way that tolerances and uniformity are tightly controlled in production to ensure lens uniformity and quality.
Directed energy techniques, such as ultrasonic welding are known in the art for permanently joining materials such as polymers without consideration for later separation. The usual goal is to attain the strongest bond possible.
It is therefore an object of the present invention to provide an apparatus and method for releasable fixing the separate pieces of an artificial eye lens mold which is capable of separation after polymerization of the monomer into an artificial eye lens.
It is a further object of the present invention to provide such a method and apparatus for fixing the mold pieces which require little or no modification to the current shape or material of the molds being used.
It is another object of the invention to provide a method and apparatus where parameters used to fix and the bond strength of the resulting secured mold pieces are easily quantifiable and variable.
It is yet another object of the present invention to provide an apparatus and method for securing artificial eye lens mold pieces that do not have a deleterious effect on the lens being made, but rather contribute to a uniform, close tolerance lens.